Residual torque analyzer

Abstract

A system for detecting fastener movement and measuring a residual torque in a fastener joint, including a device for applying torque to a stationary fastener in a tightened state and measuring torque and angle of rotation. The device includes a sensing system that has a gyroscope that provides a signal corresponding to the angle of rotation of the device as it applies torque to the fastener, and a torque transducer that provides a signal corresponding to the torque applied to the fastener by the device. The device also includes a computing unit in communication with the sensing system and adapted to receive the signal corresponding to an angle of rotation of the device and the signal corresponding to the torque applied to the fastener, and determine a torque at a moment of initial movement of the fastener.

Description

RELATED APPLICATION[0001]This application claims the benefit of: U.S. Provisional Application No. 60 / 994,624, entitled IMPROVED RESIDUAL TORQUE MEASUREMENT, filed Sep. 20, 2007; U.S. Provisional Application No. 60 / 994,837, entitled TORQUE WRENCH WITH ANALOG OR DIGITAL OUTPUT CAPABILITY, filed Sep. 21, 2007; and U.S. Provisional Application No. 60 / 995,021, entitled TORQUE ANALYZER SYSTEM, filed Sep. 24, 2007, all of which are incorporated herein in their entirety by reference.FIELD OF INVENTION[0002]The invention relates generally to residual torque detection and analysis. More specifically, the invention relates to devices, systems and methods relating to measuring residual torque in a previously-tightened fastener by detecting fastener motion.BACKGROUND OF THE INVENTION[0003]Residual torque may be defined as the torque that remains on a threaded fastener after it has been tightened, and is typically measured by applying torque to the previously-tightened fastener and observing the ...

AI Technical Summary

Benefits of technology

[0026]Further, the present invention is equally effective across all joint types, unlike known methods, including the capture angle method, and does not require estima

Problems solved by technology

For example, an under-torqued fastener may vibrate or work loose.

Conversely, if tension is too high, the fastener can snap or strip its threads.

First, there are dozens of sources of error that could cause an instrumented tool, one that initially indicated correct installation torque, to subsequently apply low actual joint torque.

In another example, a longer-than-normal extension used with a tightening tool may introduce error.

The longer extension absorbs more rotational energy intended for the joint as compared to a shorter extension, thus lowering actual applied torque.

As the gears in the right-angle drive of a power wrench collect dirt and wear, increasing friction absorbs torque and the sensor in the tool picks up less than accurate readings.

A second reason to precisely measure residual torque is the high cost of failure for many joints.

Improper torque in safety-critical applications, such as steering gears or braking assemblies, can result in significant equipment damage, human injury, or even death.

In order for these devices to effectively and accurately measure residual torque, though, a significant amount of operator training and practice is required.

The tendency to overshoot is central to many of the problems associated with using a simple peak-reading device, such as the one disclosed in Becker et al., to measure residual torque.

Slower reaction time results in greater overshoot.

In addition, since torque auditors typically take several hundred measurements in a shift, inconsistencies may creep into the process.

Fatigue may cause a weaker pull on the wrench, or pressure to meet a schedule may lead to a quicker pull and greater overshoot.

Whil

Images